Today’s religious extremism is almost entirely Islamic. While ISIS’s purge may be the most brutal, Islamists in Egypt have driven thousands of Coptic Christians from homes they’ve occupied for centuries. The same is true across the Muslim parts of Africa. This does not mean that all Muslims are extremists, but it does mean that all Muslims have an obligation to denounce and resist the extremists who murder or subjugate in the name of Allah. Too few imams living in the tolerant West will speak up against it.
As for the post-Christian West, most elites may now be nonbelievers. But a culture that fails to protect believers may eventually find that it lacks the self-belief to protect itself.